Magnetic recording media has begun to incorporate perpendicular magnetic recording (PMR) technology in an effort to increase areal density and has recently demonstrated densities of 612 Gbits/in2. Generally, PMR media may be partitioned into three functional regions: a soft magnetic underlayer (SUL), a nonmagnetic intermediate layer (NMIL) and a magnetic recording layer (RL). Well-isolated smaller grains of higher magnetic anisotropy constant (Ku) for a bottom magnetic recording layer can reduce media noise to achieve these higher areal densities. Enhanced grain isolation in a bottom magnetic recording layer of a PMR media structure, for example, can provide a smaller magnetic cluster size and narrow the size distribution.
While microstructure of a magnetic recording layer can be improved by controlling oxide content in the magnetic recording layer (e.g., bottom magnetic recording layer), enhancement of grain isolation by such means induces undesirable side effects, such as worse thermal stability, nonuniform grain isolation along the film thickness direction, broader crystallographic c-axis orientation and wider magnetic anisotropy dispersion.